CN113524702B - Method for manufacturing laminated optical film - Google Patents

Abstract

The invention provides a method for manufacturing a laminated optical film, which can inhibit the laminated optical film from generating defects caused by damage and deformation of a laminating roller. A first optical film (2) and a second optical film (3) disposed on one or both sides of the first optical film (2) via an adhesive layer or an adhesive layer are introduced between a pair of rotating laminating rollers (1, 1), and the first optical film (2) and the second optical film (3) are laminated. Here, among the pair of bonding rollers (1, 1), at least one bonding roller (1) has an outermost layer of rubber, and the elastic recovery rate of the rubber is 70% or more, so that the bonding roller (1) is less likely to be damaged, and the deformation of the bonding roller (1) is likely to be recovered.

Description

Method for manufacturing laminated optical film

This application is a divisional application of the invention patent application with the application number 201780010113.1, the application date is February 3, 2017, and the invention title is "Method for Manufacturing Laminated Optical Film".

technical field

The present invention relates to a method of manufacturing a laminated optical film.

Background technique

Conventionally, a polarizing plate is known as one of optical components constituting a liquid crystal display device or the like. In a polarizing plate, a protective film is usually laminated on one side or both sides of a polarizing film, and the mechanical strength, thermal stability, water resistance, etc. of the polarizing film are compensated.

As a lamination method of a polarizing film and a protective film, the method of bonding with a pair of bonding rolls is known. For example, in Patent Document 1, two films are bonded together using a pair of rubber rollers whose roller surfaces are rubber.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 5399890

Contents of the invention

The problem to be solved by the invention

Generally, when bonding optical films together using a bonding roll, if the bonding roll is damaged or deformed, these shapes are transferred to the optical film, resulting in the manufacture of a defective laminated optical film.

Therefore, an object of the present invention is to provide a method for producing a laminated optical film capable of suppressing the occurrence of defects in the laminated optical film due to damage and deformation of the bonding roll.

method used to solve the problem

The present invention is a method for producing a laminated optical film, wherein a first optical film is introduced between a pair of rotating lamination rolls, and a single layer of the first optical film is arranged via an adhesive layer or an adhesive layer. The second optical film on the surface side or both sides is used to bond the first optical film and the second optical film. Among the pair of bonding rollers, the outermost layer of at least one bonding roller is rubber, and the elasticity of the rubber is restored. The rate is over 70%.

In the manufacturing method of this laminated optical film, the outermost layer of at least one of the bonding rollers in the pair of bonding rollers is rubber, and its elastic recovery rate is 70% or more. Therefore, the bonding roller is difficult to be damaged, and the bonding The deformation of the roller is easy to recover. Therefore, according to the manufacturing method of this laminated optical film, generation|occurrence|production of a defect in a laminated optical film by damage and deformation|transformation of a bonding roll can be suppressed.

Here, at least one of the second optical films may be a transparent film.

And, the transparent film may be a protective film, and the first optical film may be a polarizing film. Furthermore, the polarizing film may contain polyvinyl-alcohol-type resin.

In the manufacturing method of the laminated optical film, the polarizing film may have a thickness of 20 μm or less, the protective film may have a thickness of 30 μm or less, and the laminated optical film may have a thickness of 100 μm or less. In general, the thinner the thickness of the laminated optical film, the easier it is for defects due to damage and deformation of the bonding roll to occur. Therefore, it can be said that each film having such a thickness is suitable for applying the present invention.

As another aspect of the manufacturing method of the laminated optical film, the first optical film may be a polarizing plate including a polarizing film and a protective film, and the first optical film and the second optical film may be bonded via an adhesive layer.

In this embodiment, the thickness of the polarizing film may be 20 μm or less, the thickness of the protective film may be 30 μm or less, and the thickness of the polarizing plate may be 100 μm or less.

In any of the above-mentioned production methods, the rubber hardness of the rubber measured in accordance with JIS K 6253 may be 83° to 97°. Even with this rubber hardness, if the elastic recovery rate satisfies the above value, the effect of the present invention will be exhibited.

In any of the above-mentioned manufacturing methods, the outermost layers of the pair of bonding rollers may be rubber, and the elastic recovery rate of the rubber may be 70% or more. In this case, the effects of the present invention can be exhibited more favorably.

In any of the above-mentioned manufacturing methods, at least one pressing roll may be brought into contact with at least one bonding roll among a pair of bonding rolls, and the bonding roll may be pressed in a direction in which the pair of bonding rolls approach each other. In this case, since it is easy to apply a uniform load to the width direction of a bonding roll, it is preferable.

The effect of the invention

According to the present invention, it is possible to provide a method for producing a laminated optical film capable of suppressing the occurrence of defects in the laminated optical film due to damage and deformation of the bonding roll.

Description of drawings

FIG. 1 is a schematic diagram of how each film is bonded by a pair of bonding rolls.

Fig. 2 is a cross-sectional view of the polarizing plate according to the first embodiment.

Fig. 3 is an explanatory diagram of a calculation method of an elastic recovery rate.

(a) of FIG. 4 is a cross-sectional view of the polarizing plate with adhesive according to the second embodiment. (b) of FIG. 4 is a cross-sectional view of another adhesive-attached polarizing plate according to the second embodiment.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the same code|symbol is attached|subjected to the same part or a corresponding part, and repeated description is abbreviate|omitted. In addition, the dimensional ratios in the respective drawings do not necessarily match the actual dimensional ratios, and the thicknesses in particular are described exaggeratedly.

<First Embodiment>

As 1st Embodiment, the example which bonded the polarizing film which is a 1st optical film, and the protective film which is a 2nd optical film, and manufactured the polarizing plate which is a laminated optical film is shown.

As shown in FIG. 1 , the polarizing film 2 and the protective films 3 and 3 disposed on both surfaces thereof are introduced between a pair of rotating bonding rollers 1 and 1 while being conveyed, to form a laminated film 4 in which both films are laminated.

Here, just before the polarizing film 2 and the protective films 3, 3 are introduced into a pair of bonding rollers 1, 1, the polarizing film 2 and the protective films 3, 3 are sandwiched between the adhesive layers 5, 5 (see FIG. 2). As a method of sandwiching the adhesive layer 5, an adhesive may be applied to both surfaces of the polarizing film 2, or an adhesive may be applied to the surface of the protective films 3 and 3 that faces the polarizing film 2. way of adhesive. The polarizing film 2 and the protective films 3, 3 are bonded together via an adhesive.

When bonding, the pair of bonding rollers 1, 1 can be pressed by a pair of pressing rollers 6, 6 provided so as to be in contact therewith. Here, a pair of pressing roll 6,6 is installed in the position which pinches the bonding roll 1,1 on the straight line which connects a pair of bonding roll 1,1. And the pressing rolls 6, 6 are pressed in the direction in which the bonding rolls 1, 1 approached each other. Since it is easy to apply uniform load to the width direction of the bonding roll 1, 1 when the pressing roll 6,6 is used, it is preferable. In addition, the pressing roll does not necessarily need to be paired, and the form which presses one bonding roll with one pressing roll may be sufficient.

Both the bonding rollers 1, 1 and the pressing rollers 6, 6 are rotatable. By rotationally driving at least one of the bonding rolls 1, 1 and the pressing rolls 6, 6, the bonding rolls 1, 1 rotate, and the polarizing film 2 and the protective films 3, 3 can be bonded and conveyed. The roller that is not driven to rotate rotates as the roller that is in contact is driven to rotate.

In the laminated film 4 passed through the pair of bonding rolls 1, 1, the polarizing film 2 and the protective films 3, 3 are adhered via the adhesive layers 5, 5. The laminated film 4 is then cured by the adhesive layer 5 to complete the polarizing plate (laminated optical film) 10 shown in FIG. 2 .

Polarizing plate 10 is formed by laminating protective films 3 on both surfaces of polarizing film 2 via adhesive layer 5 .

As the material of the polarizing film 2, known materials conventionally used to manufacture polarizing plates can be used, such as polyvinyl alcohol-based resins, polyvinyl acetate resins, ethylene/vinyl acetate (EVA) resins, polyamide resins, Polyester resin, etc.

Among them, polyvinyl alcohol-based resins are preferable. Usually, as a production starting material of the polarizing film 2 , for example, an unstretched film of a polyvinyl alcohol-based resin film having a thickness of 5 to 100 μm, preferably 10 to 80 μm is used. The polarizing film 2 is obtained by subjecting this unstretched film to dyeing treatment, boric acid treatment, and stretching treatment.

The thickness of the polarizing film 2 is preferably 3 to 20 μm, more preferably 5 to 18 μm, and still more preferably 7 to 16 μm.

The protective film 3 is a film which prevents the main surface and the edge part of the polarizing film 2 from cracking and damage. Here, the "protective film" refers to a film that is physically laminated at a position closest to the polarizing film 2 among various films that can be laminated on the polarizing film 2 .

The protective film 3 is preferably composed of various transparent resin films known in the field of polarizing plates. Examples include cellulose-based resins typified by triacetyl cellulose, polyolefin-based resins typified by polypropylene-based resins, cyclic olefin-based resins typified by norbornene-based resins, polyolefin-based resins typified by Methyl methacrylate resin is a typical example of acrylic resin, polyethylene terephthalate resin is a representative example of polyester resin, and the like. Among them, a representative product is a cellulose-based resin.

Here, the protective film being "transparent" means that the total light transmittance measured in accordance with JIS K 7361 is 70% or more.

The protective films 3 and 3 may be formed of the same material or may be formed of different materials.

The protective film 3 may be a film that does not have an optical function, or may be a film that has an optical function such as a retardation film or a brightness enhancement film.

The thickness of the protective film 3 is preferably 5 to 30 μm, more preferably 7 to 27 μm, even more preferably 9 to 25 μm.

As an adhesive, various adhesives conventionally used for manufacturing a polarizing plate can be used. For example, from the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., an epoxy resin that does not contain an aromatic ring in the molecule is preferable. Moreover, it is preferable to cure by irradiation of an active energy ray (ultraviolet ray or heat ray).

As an epoxy resin, hydrogenated epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. are preferable, for example. By adding a polymerization initiator (for example, a photocationic polymerization initiator for polymerization by ultraviolet irradiation, a thermal cationic polymerization initiator for polymerization by heat ray irradiation) and other additives (increasing sensitizer, etc.) can be prepared and used as an epoxy resin composition for coating.

In addition, as the adhesive, acrylic resins such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate; and polyvinyl alcohol-based water-based adhesives can also be used.

The polarizing plate 10 is bonded to one or both surfaces of a display cell (image display element) such as a liquid crystal cell. The polarizing plate 10 may further include other optical layers laminated on the protective film 3 . Examples of other optical layers include a reflective polarizing film that transmits a certain polarized light and reflects polarized light exhibiting an opposite property; a film with an anti-glare function having an uneven surface; a film with an anti-reflection function on the surface; Reflective film with reflective function on the surface; semi-transmissive reflective film with both reflective and transmissive functions; viewing angle compensation film, etc.

The thickness of the polarizing plate 10 formed of three layers of the polarizing film 2 and the protective films 3 and 3 is preferably 20 to 100 μm, more preferably 25 to 90 μm, and even more preferably 30 to 80 μm.

The outermost layers of the pair of bonding rollers 1 and 1 are both formed of rubber. The bonding rollers 1 and 1 may be formed entirely of rubber, or may be formed of metal at the center and only the outermost layer may be formed of rubber. In addition, as another aspect, the outermost layer of one bonding roller 1 may be formed of rubber, and the outermost layer of the other bonding roller 1 may be formed of metal. That is, among a pair of bonding roll 1,1, at least one outermost layer should just be formed with rubber.

The roll diameter of the bonding rolls 1 and 1 is preferably 50 to 500 mm, more preferably 80 to 450 mm, and still more preferably 100 to 400 mm. If the roll diameters of the bonding rolls 1 and 1 are in such a range, it is easy to apply a sufficient linear pressure to each film during bonding, and it is easy to suppress generation of wrinkles, bubbles, etc. in the laminated film 4 .

The thickness of the rubber layer is preferably 1 to 50 mm, more preferably 5 to 40 mm, still more preferably 10 to 30 mm, particularly preferably 10 to 20 mm. If the thickness of the rubber layer is too thin, the influence of the metal roller is strong, and wrinkles and the like are likely to be generated in the film during lamination. On the other hand, if the thickness of the rubber layer is too thick, the linear pressure against the laminated films during lamination may become insufficient, and defects such as air bubbles may occur in the laminated film 4 . Moreover, since it will take a lot of time to manufacture a rubber roller when the thickness of a rubber layer is too thick, it is not preferable from an economical point of view. In addition, from a viewpoint of the adhesiveness of a rubber layer and a metal roller, the rubber layer may laminate|stack multiple types of materials with a different composition.

The elastic recovery rate of this rubber is 70% or more. The elastic recovery rate is preferably 75% or more, more preferably 80% or more, and still more preferably 85% or more, from the viewpoint that the surface of the rubber is less likely to be damaged and the generated deformation is easily recovered during lamination. Examples of the upper limit of the elastic recovery rate include 99%, 97%, 95%, and the like.

Here, the "elastic recovery rate" means: when a press-fitting workload (押込み供力) is applied to a part exhibiting plastic deformation and elastic deformation, the elastic The scale in which the deformation is involved.

The elastic recovery rate can be measured using a microhardness meter (for example, product name "Fisher Scope HM2000", manufactured by Fisher Instruments). That is, a square cone Vickers indenter (made of diamond, with a face angle of 136°) can be pressed into the test object from the surface at a load speed of 350mN/10s. After reaching the maximum load of 350mN, the load reaches the maximum load Hold it for 10s in the state of the test object, and then remove the Vickers indenter from the surface of the test object at an unloading speed of 350mN/10s, and obtain it from the test load and indentation depth at this time.

Specifically, the relationship between the indentation depth (h) and the observed test load size (F) when the Vickers indenter is pressed into the test object is shown in a table, as shown in FIG. 3 .

Here, h on the horizontal axis represents the length of the portion pressed into the test object among the heights of the Vickers indenter. The Vickers indenter is pressed in from the measurement start point t ₀ until t ₂ is passed through t ₁ , and then t ₃ is reached when the indentation is released. The intrusion depth h _p at _t3 becomes a value smaller than the indentation depth _hc predicted when the relaxation at _t2 is linear. Here, the area surrounded by the points t ₀ to t ₃ is the working load (W _plast ) of plastic deformation, and the line t ₂ -t ₃ that is generated when it is relieved at the time of release press-in passes through t ₂ and is parallel to The area surrounded by the h _maX line on the vertical axis and the horizontal axis is the working load (We _last ) of elastic deformation.

Here, the elastic recovery rate is a value defined as follows:

Elastic recovery rate (%)={ _Welast /( _Welast + _Wplast )}×100.

Examples of the rubber material of the outermost layer of the bonding roller 1 include NBR (acrylonitrile-butadiene rubber), urethane rubber, silicone rubber, EPDM rubber, butyl rubber, and fluororubber.

The rubber hardness of the rubber is preferably 83 to 97°, more preferably 85 to 97°, even more preferably 85 to 90° when measured in accordance with JIS K 6253-3 (2012). In general, the elastic recovery rate tends to increase as the value of the rubber hardness decreases. However, in the present embodiment, the elastic recovery rate shows a desired value even if the rubber hardness is within the above-mentioned range.

The material of pressing roller 6,6 can be metal, also can be rubber. In the case of rubber, the elastic recovery rate and rubber hardness include the same numerical ranges as the elastic recovery rate and rubber hardness of the rubber in the bonding roller 1 as preferable values.

Preferable conditions for the pressure applied to the film nipped by the bonding rollers 1 and 1 at the time of bonding are not particularly limited, but are preferably 0.01 to 10 MPa, more preferably 0.1 to 5 MPa. When the said pressure is large, it exists in the tendency for the defect by damage and deformation of the bonding rolls 1 and 1 to generate|occur|produce easily. Moreover, when the said pressure is small, there exists a tendency for a defect, such as a bubble, to generate|occur|produce without uniform bonding.

Preferable conditions for the tension applied to each film at the time of lamination vary depending on the material of the film, lamination temperature, etc., and for the film before lamination, it is preferably 10 to 1000 N/m, more preferably 50 to 500 N/m . In addition, the tension applied to the bonded film is preferably 10 to 2000 N/m, more preferably 100 to 1500 N/m. When the tension is within the above-mentioned range, it becomes more difficult for the film to wrinkle and sag, and the possibility of elongation or breakage of the film can be further reduced.

In the manufacturing method of the polarizing plate 10 described above, the outermost layer of the pair of bonding rolls 1, 1 is rubber, and its elastic recovery rate is 70% or more, so the bonding rolls 1, 1 are less likely to be damaged or deformed. Moreover, even if damage and deformation|transformation generate|occur|produce in the bonding roller 1, 1, these are hard to transfer to the polarizing plate 10. Therefore, according to the manufacturing method of this polarizing plate 10, generation|occurrence|production of the defect in the polarizing plate 10 by damage and deformation of the bonding rolls 1 and 1 can be suppressed.

In particular, the smaller the thickness of the film to be bonded or the polarizing plate to be manufactured, the more likely defects are caused by damage and deformation of the bonding roll, so it can be said that this manufacturing method is suitable for bonding thin films. . In addition, in lamination of a thin film, by setting the elastic recovery rate and rubber hardness to the above values, it is easy to control appearances such as surface defects (muscle defects) and streaks satisfactorily.

It should be noted that, in the above-mentioned embodiment, the example (three pieces of bonding) of the protective films 3 and 3 bonded on both sides of the polarizing film 2 has been shown, but it may be made to bond the protective film only on one side of the polarizing film 2. The way of film 3 (two pieces pasted together).

In addition, in the said embodiment, the example where the 1st optical film was the polarizing film 2 and the 2nd optical film was shown as the protective films 3 and 3 was shown, but these may be other types of films. In addition, the films bonded on both surfaces of the polarizing film 2 do not necessarily need to be of the same kind, and may be of different kinds.

<Second Embodiment>

As 2nd Embodiment, the example which manufactures the "polarizing plate with an adhesive agent" which is a laminated optical film by bonding a polarizing plate as a 1st optical film and another optical film as a 2nd optical film together is shown. Hereinafter, points different from the first embodiment will be described.

As shown in FIG. 4( a ), the adhesive-attached polarizing plate 20A manufactured in the manufacturing method of the present embodiment is bonded to one side of the polarizing plate 10 manufactured in the first embodiment via the adhesive layer 7. There is a temporary protective film (second optical film) 8 .

The temporary protective film 8 is a film that can be peeled from the polarizing plate 10 laminated thereon, and is a film for protecting the surface of the protective film 3 laminated with the temporary protective film 8 from damage, abrasion, and the like. As the material of the temporary protective film 8, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, etc. As the ester resin, the same material as that of the protective film 3 can be used.

Other plastic films such as polyolefin films, polyacetate films, polycarbonate films, polyphenylene sulfide films, polyamide films, polychloride films, etc. Vinyl film, ethylene-vinyl acetate copolymer film, various liquid crystal polymer films, etc.

After being laminated on the protective film 3 , the temporary protective film 8 is bonded to the protective film 3 until the adhesive-attached polarizing plate 20A is used, and is peeled off from the protective film 3 when used. At this time, the adhesive layer 7 is peeled from the polarizing plate 10 side in the state attached to the temporary protective film 8 side.

The thickness of the temporary protective film 8 is preferably 5 to 70 μm, more preferably 10 to 60 μm, and still more preferably 15 to 50 μm.

The adhesive layer 7 can be made of acrylic resin, silicone resin, polyester, polyurethane, polyether, or the like.

The thickness of the adhesive layer 7 is preferably 2 to 40 μm, more preferably 4 to 25 μm.

As a method of providing the adhesive layer 7, for example, on the temporary protective film 8, various types of acrylic one-part or two-part adhesives, rubber-based adhesives, and silicone-based adhesives can be used. In the method of forming the adhesive layer 7 with an adhesive or the like, and then laminating it on the protective film 3, usually the adhesive layer is temporarily wound into a roll in a state where the adhesive layer is covered with a release film. Use after peeling off the release film before attaching two pieces. In addition, a method of coating a solution containing the above-mentioned resin and optional additive components on the protective film 3 of the polarizing plate 10 may be used. After the adhesive layer 7 is provided, the polarizing plate 10 and the temporary protective film 8 are bonded together with a pair of bonding rolls shown in FIG. 1 (two-sheet bonding) to manufacture an adhesive-attached polarizing plate 20A.

Also in this embodiment, it is possible to suppress occurrence of defects in the adhesive-attached polarizing plate 20A due to damage or deformation of the bonding rollers 1 and 1 .

The example in which the second optical film is the temporary protective film 8 has been described above, but the second optical film may be a separator 9 instead of the temporary protective film 8 as shown in FIG. 4( b ).

Separator 9 is a peelable film bonded for the purpose of protecting adhesive layer 7 and preventing foreign matter from adhering, and is peeled off to expose adhesive layer 7 when polarizing plate 20B with adhesive is used. The separator 9 can be made of, for example, polyethylene-based resin such as polyethylene, polypropylene-based resin such as polypropylene, polyester-based resin such as polyethylene terephthalate, or the like. Among them, a stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive layer 7 on which the separator 9 is laminated is a layer that functions when the polarizing plate 10 is bonded to another article (for example, a liquid crystal cell, a touch panel). As the material of the adhesive layer 7, the same material as that used when laminating the temporary protective film 8 can be used.

The separator 9 may be subjected to a release treatment using silicone resin or the like on the surface in contact with the adhesive layer 7 in order to allow easy peeling when the polarizing plate 20B with an adhesive is used. When the separator 9 is peeled off, the adhesive layer 7 remains on the polarizing plate 10 side.

The thickness of the separator 9 is preferably 5 to 70 μm, more preferably 10 to 60 μm, even more preferably 15 to 50 μm.

In addition, in this embodiment, the polarizing plate 10 has shown the example which further has the polarizing plate 20A, 20B with an adhesive of the temporary protective film 8 or the separator 9, but the polarizing plate 20A, 20B with an adhesive Both the temporary protective film 8 and the diaphragm 9 may be provided.

As mentioned above, although preferred embodiment of this invention was demonstrated, this invention is not limited to the said embodiment at all. For example, in the said embodiment, the film which has polarizing property was illustrated as a 1st optical film, However, Other optical films which do not have polarizing property may be made into objects.

Example

Hereinafter, an Example and a comparative example are given, and the content of this invention is demonstrated more concretely. In addition, this invention is not limited to a following example.

The membranes used are shown below.

- Polarizing film... obtained by stretching and drying the polyvinyl-alcohol-type resin film (trade name "VF-PE#3000", manufactured by Kuraray Co., Ltd.) with iodine. The thickness is 12 μm.

- Protective film A...triacetyl cellulose film (trade name "KONICA MINOLTA OPTICAL FILMKC2UAW", manufactured by Konica Minolta Advanced Layer Co., Ltd.). The thickness is 25 μm.

- Protective film B...Cyclic olefin resin film (trade name "ZEONOR FILM ZF14-23", manufactured by Nippon Zeon Corporation). The thickness is 23 μm.

・Temporary protective film with adhesive...a film formed of a base film of polyethylene terephthalate and an adhesive layer of acrylic resin (trade name "AS3-304(19)", Fujimori Kogyo corporation). The thickness was 58 μm (the thickness of the substrate film itself after removing the adhesive layer was 38 μm).

・Separator with adhesive...A film formed of a polyethylene terephthalate separator subjected to mold release treatment and an acrylic resin adhesive (trade name "#L2-NCF", manufactured by LINTEC Corporation) ). The thickness was 43 μm (thickness of the separator itself after removing the adhesive layer was 38 μm).

The adhesive was prepared as follows. In 100 parts by weight of water, 4 parts by weight of acetoacetyl-modified polyvinyl alcohol (trade name "Gohsefimer Z-200", manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and sodium glyoxylate (trade name "SPM-01", Nippon Synthetic Chemical Industry Co., Ltd.) 4 parts by weight to prepare a water-based adhesive.

The rubber material used for laminating rollers and pressing rollers is produced by the following method.

The NBR polymer, sulfur, silica, and phthalic acid-based plasticizer are measured so as to have a predetermined weight ratio, kneaded by a kneader, and then molded into a roll shape by sheet molding and used. The composition of the manufactured rubber material was made into the following weight ratio.

·Rubber material A

NMR polymer: sulfur: silica: phthalic acid-based plasticizer = 100:12:60:9.

·Rubber material B

NMR polymer: sulfur: silica: phthalic acid-based plasticizer = 100:7:60:8.

·Rubber material C

NMR polymer: sulfur: silica: phthalic acid-based plasticizer = 100:8:70:3.

Table 1 shows the elastic recovery rate (%) and hardness (°) of the produced rubber material.

The rollers used are as follows.

・Laminating roller with outermost layer made of rubber...The overall diameter of the roller is 300mm, and the thickness of the outermost rubber material is 16.5mm. As the rubber material, the aforementioned rubber materials A, B, and C were used.

・Metal roller...Made of stainless steel.

·Press roller...The rubber material is the above-mentioned rubber material A.

(Example 1 and 2)

Using the bonding rolls shown in Table 1, the protective film A was bonded to one surface of the polarizing film, and the protective film B was bonded to the other surface (three-sheet bonding) to obtain a polarizing plate. At this time, the adhesive is applied on the polarizing film side. The obtained polarizing plate had a thickness of 60 μm.

(Example 3)

Using the bonding rolls shown in Table 1, the polarizing plate produced in Example 1 and the temporary protective film with adhesive were bonded (two-sheet bonding) to obtain a polarizing plate with adhesive.

(Example 4)

Using the bonding roll shown in Table 1, the polarizing plate produced in Example 1 and the separator with adhesive were bonded together (two-sheet bonding) to obtain a polarizing plate with adhesive.

(Example 5)

Using the bonding rolls shown in Table 1, the protective film A was bonded to one surface of the polarizing film, and the protective film B was bonded to the other surface (three-sheet bonding) to obtain a polarizing plate. At this time, the adhesive is applied on the polarizing film side. In addition, the metal roller is pressed against the rubber roller using a pressing roller. The obtained polarizing plate had a thickness of 60 μm.

(comparative example 1)

Using the bonding rolls shown in Table 1, the protective film A was bonded to one surface of the polarizing film, and the protective film B was bonded to the other surface (three-sheet bonding) to obtain a polarizing plate. At this time, the adhesive is applied on the polarizing film side. The obtained polarizing plate had a thickness of 60 μm.

The surfaces of the polarizing plates obtained in Examples 1 to 5 and Comparative Example 1 and the polarizing plate with adhesive were observed visually. The results are shown in Table 1.

·Evaluation mark

A...No defect was observed.

B... A defect (within an allowable range) which may be considered to be damage or deformation of the bonding roller transferred was slightly observed.

C... Many defects thought to be damage or deformation of the bonding roller transferred were observed.

[Table 1]

[Table 1]

Explanation of reference signs

1...bonding roll, 2...polarizing film (first optical film), 3...protective film (second optical film), 4...laminated film, 5...adhesive layer, 6...pressing roll, 7...adhesive Layer, 8...temporary protective film (second optical film), 9...separator (second optical film), 10...polarizing plate (laminated optical film, first optical film), 20A, 20B...polarizing plate with adhesive (laminated optical film).

Claims (7)

1. A method for producing a laminated optical film, wherein a first optical film and a second optical film disposed on one or both sides of the first optical film via an adhesive layer or an adhesive layer are introduced between a pair of lamination rollers which rotate, the first optical film and the second optical film are laminated,

the first optical film is a polarizing plate having a polarizing film and a protective film,

the polarizing film has a thickness of 20 μm or less,

the thickness of the protective film is 30 μm or less,

the thickness of the polarizing plate is 60 μm or less,

at least one of the pair of laminating rollers has an outermost layer of rubber,

the elastic recovery rate of the rubber is more than 70 percent,

the tension applied to the film before bonding is 50N/m to 500N/m, and the tension applied to the film after bonding is 100N/m to 1500N/m.

2. The method for producing a laminated optical film according to claim 1, wherein at least 1 sheet among the second optical films is a transparent film.

3. The method for producing a laminated optical film according to claim 2, wherein the transparent film is a protective film.

4. The method for producing a laminated optical film according to claim 1, wherein the polarizing film comprises a polyvinyl alcohol resin.

5. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein the rubber has a rubber hardness of 83 to 97 ° measured in accordance with JIS K6253.

6. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein the outermost layers of the pair of laminating rollers are each rubber,

the elastic recovery rate of the rubber is more than 70%.

7. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein at least 1 pressing roller is brought into contact with at least one bonding roller of the pair of bonding rollers, and the bonding rollers are pressed in a direction in which the pair of bonding rollers approach each other.

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